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| Study on the Influence of Number Distribution of Calibration Points on CTD(temperature) Calibration |
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Abstract Aiming at the status quo of long calibration period and high cost of 8-point (0℃~35℃) salt depth measuring instrument CTD(measuring accuracy ±2mK), this paper counted 30 CTD calibration results based on the high-precision seawater constant temperature tank calibration device, and initially explored the influence of the number of CTD calibration points (4, 6, 8) distribution on the calibration results. The 4-point distribution calibration results can basically meet the measurement accuracy range of (±2mK), but about one-third of CTD always has some temperature point fitting residuals beyond the measurement accuracy, which cannot meet the high-precision CTD calibration. The calibration results at 6 points (35℃, 25℃, 15℃, 10℃, 5℃, 0℃) are all within the range of its measurement accuracy (±2mK), meeting the CTD calibration of measurement accuracy (±2mK). CTD(11858) was selected to evaluate its calibration repeatability and calibration deviation. The calibration repeatability of 6 point and 8 point were 0.8mK and 0.5mK, respectively. Calibration deviation of 6 and 8 points is within 0.5mK. The calibration uncertainty is better than U=1.5mK(k=2), and the experimental results show that 6-point (35℃, 25℃, 15℃, 10℃, 5℃, 0℃) calibration is feasible to replace 8-point calibration. The results are helpful to shorten the CTD calibration cycle, reduce the calibration cost, improve the efficiency of Marine survey and guarantee the quality of Marine survey data.
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Received: 18 October 2024
Published: 03 April 2025
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2025, Vol. 46 
